Rubber vulcanization accelerator composition

Abstract

The present invention is based on the discovery of an accelerator composition for the vulcanization of diene elastomers, comprising a benzothiazole sulfenamide, a thiuram sulfide and copper 2-mercaptobenzothiazole.

I claim: 
     
       1. A rubber vulcanization accelerator composition comprising (a) from about 0.1 to 1.5 parts of a benzothiazole-2-sulfenamide, (b) from about 0.02 to 1.5 parts of a thiuram sulfide or a metal dithiocarbamate, said metal being selected from the group consisting of zinc, cadmium, tellurium, bismuth, nickel, selenium and lead, and (c) from about 0.002 to 1.5 parts of copper 2-mercaptobenzothiazole per each 100 parts of said rubber; the weight ratio of said components (a), (b) and (c) being in the range from about 10:1:0.05 to 1:1:1, respectively. 
     
     
       2. The composition according to claim 1 wherein said benzothiazole-2-sulfenamide is N-oxydiethylene benzothiazole-2-sulfenamide. 
     
     
       3. The composition according to claim 1 wherein said benzothiazole-2-sulfenamide is N-cyclohexyl benzothiazole-2-sulfenamide. 
     
     
       4. The composition according to claim 1 wherein said benzothiazole-2-sulfenamide is N-tert-butyl benzothiazole-2-sulfenamide. 
     
     
       5. The composition according to claim 1 wherein said benzothiazole-2-sulfenamide is N,N-diisopropyl benzothiazole-2-sulfenamide. 
     
     
       6. The composition according to claim 1 wherein said benzothiazole-2-sulfenamide is N,N-dicyclohexyl benzothiazole-2-sulfenamide. 
     
     
       7. The composition according to claim 1 wherein said thiuram sulfide is tetramethyl thiuram monosulfide. 
     
     
       8. The composition according to claim 1 wherein said thiuram sulfide is tetramethyl thiuram disulfide. 
     
     
       9. The composition according to claim 1 wherein the metal dithiocarbamate is zinc dimethyl dithiocarbamate. 
     
     
       10. A method for increasing the processing safety of a rubber vulcanization accelerator composition comprising (a) from about 0.1 to 1.5 parts of a benzothiazole-2-sulfenamide, and (b) from about 0.02to 1.5 parts of a thiuram sulfide or a metal dithiocarbamate, said metal being selected from the group consisting of zinc, cadmium, tellurium, bismuth, nickel, selenium and lead; which comprises adding from about 0.002 to 1.5 parts of copper 2-mercaptobenzothiazole per each 100 parts of said rubber, the weight ratio of components (a) and (b) to the copper 2-mercaptobenzothiazole being in the range from about 10:1:0.05 to 1:1:1.